Various forms of grain dryers heretofore have been provided. For the most part, grain dryers cause heated drying air to pass through grain to be dried. However, if the grain is retained in the dryer in a heated condition or is withdrawn from the dryer in a heated condition certain ambient temperature and humidity conditions tend to cause the grain to mildew, especially if the grain is discharged from the dryer at a temperature higher than ambient temperature. Also, inasmuch as conventional grain dryers tend to discharge grain from the dryer at a temperature higher than ambient temperature, considerable energy loss from the drying system is inherent due to the discharge of hot grain from the dryer. Accordingly, a need exists for a grain dryer which may be operated more efficiently and which will be capable of discharging grain from the dryer at a temperature no greater than ambient temperature and less than ambient temperature, if desired.
Examples of various forms of previous known grain dryers, including some of the general structural and operational features of the instant invention, are disclosed in U.S. Pat. Nos. 3,233,337, 3,739,487, 3,931,683, 4,004,351, 4,134,216 and 4,144,654.